Forehead Movement Discrepancies After Botulinum Toxin Injections: A Review of Etiology, Correction, and Prevention.

BACKGROUND: Forehead rhytides are a popular target for botulinum toxin injections, but neuromodulation of the frontalis can be fraught with complications because of its anatomic complexity and integral role in brow position and expressivity. OBJECTIVE: This article explores common forehead movement discrepancies that can occur after neuromodulation of the frontalis, as well as how to correct and prevent them. METHODS: A review of the literature was conducted and combined with clinical experience to examine underlying forehead anatomy, etiology and correction of forehead movement discrepancies, and important factors to consider before injecting the frontalis with botulinum toxin. RESULTS AND CONCLUSION: Variable anatomy from person to person necessitates an individualized treatment approach to achieve the best cosmetic results and prevent the occurrence of forehead movement discrepancies.

Reliability of alternative devices for postoperative patient temperature measurement: two prospective, observational studies.

Peri-operative hypothermia is associated with significant morbidity, yet limitations exist regarding non-invasive temperature assessment in the post-anaesthesia care unit (PACU). In this prospective study of 100 patients, we aimed to determine the reliability of two commonly used temperature measurement devices, forehead temporal artery temperature and tympanic measurement, in addition to an indwelling urinary catheter with temperature probe, in comparison with the final nasopharyngeal core temperature at the end of surgery. Agreement of forehead measurement with nasopharyngeal temperature showed a mean bias (±95% limits of agreement) of 0.15 °C (±1.4 °C), with a steep slope of the relationship on the Bland-Altman plot of -0.8, indicating a tendency to normalise patient temperature readings to 36.4 °C. Only 54% of hypothermic cases were correctly detected by the forehead measurement device. Agreement of tympanic measurement with nasopharyngeal core temperature measurement was marginally improved with a mean bias of 0.13 °C (95% limits of agreement ±1.15 °C). In contrast, agreement of bladder temperature with nasopharyngeal temperature showed a mean (SD) bias of 0.19 (0.28) °C (95% limits of agreement ±0.54 °C), with a relatively flat line of best fit. We demonstrated that two commonly used temperature measurement devices, forehead temporal artery temperature and tympanic measurement, compared with nasopharyngeal core temperature, were imprecise and unreliable following major surgery. However, the indwelling catheter with temperature sensor was precise and acceptable for continuous core temperature measurement in the PACU.

Temperature should not be measured on forearm with infrared thermometers for Covid-19 screening.

Not available.

Expressure: Detect Expressions Related to Emotional and Cognitive Activities Using Forehead Textile Pressure Mechanomyography.

We investigate how pressure-sensitive smart textiles, in the form of a headband, can detect changes in facial expressions that are indicative of emotions and cognitive activities. Specifically, we present the Expressure system that performs surface pressure mechanomyography on the forehead using an array of textile pressure sensors that is not dependent on specific placement or attachment to the skin. Our approach is evaluated in systematic psychological experiments. First, through a mimicking expression experiment with 20 participants, we demonstrate the system's ability to detect well-defined facial expressions. We achieved accuracies of 0.824 to classify among three eyebrow movements (0.333 chance-level) and 0.381 among seven full-face expressions (0.143 chance-level). A second experiment was conducted with 20 participants to induce cognitive loads with N-back tasks. Statistical analysis has shown significant correlations between the Expressure features on a fine time granularity and the cognitive activity. The results have also shown significant correlations between the Expressure features and the N-back score. From the 10 most facially expressive participants, our approach can predict whether the N-back score is above or below the average with 0.767 accuracy.

Design of Multi-Wavelength Optical Sensor Module for Depth-Dependent Photoplethysmography.

The multi-wavelength photoplethysmography sensors were introduced to measure depth-dependent blood volume based on that concept that the longer the light wavelength, the deeper the penetration depth near visible spectrum band. In this study, we propose an omnidirectional optical sensor module that can measure photoplethysmogram while using multiple wavelengths, and describe implementation detail. The developed sensor is manufactured by making a hole in a metal plate and mounting an LED therein, and it has four wavelength LEDs of blue (460 nm), green (530 nm), red (660 nm), and IR (940 nm), being arranged concentrically around a photodetector. Irradiation light intensity was measured by photoluminescent test, and photoplethymogram was measured with each wavelength simultaneously at a periphery of the human body such as fingertip, earlobe, toe, forehead, and wrist, in order to evaluate the developed sensor. As a result, the developed sensor module showed a linear increase of irradiating light intensity according to the number of LEDs increases, and pulsatile waveforms were observed at all four wavelengths in all measuring sites.

Internal precooling decreases forehead and core temperature but does not alter choice reaction time during steady state exercise in hot, humid conditions.

This study aimed to determine if precooling via crushed ice ingestion reduces forehead skin temperature (Thead) and core temperature (Tcore) during exercise in the heat and whether it has an effect on choice reaction time (CRT). Ten males commenced a 30 min precooling period, ingesting either 7 g kg-1 of crushed ice (ICE) or room temperature water (CON) prior to cycling 60 min at 55% V̇O2peak in hot, humid conditions (35.0 ± 0.3 °C, 50.2 ± 2.1% Relative Humidity). The CRT task was completed upon arrival and after the precooling period in the lab, then at 15 min intervals during exercise in the heat. Precooling reduced Thead and Tcore to a greater degree in ICE (Thead: -0.8 ± 0.31 °C; Tcore: -0.9 ± 0.3 °C) compared with CON (Thead: -0.2 ± 0.3 °C; Tcore: -0.2 ± 0.2 °C) (p ≤ 0.001). Choice reaction time performance improved throughout the cycle for both conditions (p ≤ 0.05). Ice ingestion lowered thermal sensation (p = 0.003) and skin temperature (d = 0.88; Tskin), while heart rate, ratings of perceived exertion and thirst were similar between conditions (p > 0.05). Precooling effectively reduced Thead and Tcore but did not provide additional improvement in CRT during moderate exercise in the heat. Further investigation is required to determine whether the lower central and peripheral temperature after ice ingestion is beneficial for tasks of greater cognitive effort.

Detailed Anatomy of Osteoperiosteal Ligamentous Structures in the Forehead.

This study aimed to present the anatomic characteristics of osteoperiosteal ligamentous attachments of the forehead and provide a better understanding of lateral eyebrow descent for safe and effective foreheadplasty. Anatomic dissections of the face were performed in 10 fresh Korean adult cadavers (20 hemifaces) using 2.5× magnification surgical loupes. Supraorbital, inferomedial orbital, and frontonasal osteoperiosteal ligamentous attachments were identified as fibrous tissues originating from a bone, and their tensile strengths were measured. The supraorbital osteoperiosteal ligamentous attachment had medial and lateral parts. It can be classified into 4 subtypes. It was located 11.0 ±â€Š6.6 mm lateral to the midline and 9.2 ±â€Š12.3 mm superior to the superior orbital margin. The inferomedial orbital osteoperiosteal ligamentous attachment was located 16.2 ±â€Š3.9 mm lateral to the midline and 2.2 ±â€Š2.7 mm inferior to the superior orbital margin, whereas the frontonasal osteoperiosteal ligamentous attachment was located 5.4 ±â€Š2.3 mm lateral to the midline and 1.4 ±â€Š8.5 mm superior to the superior orbital margin. Tensile strengths of all the osteoperiosteal ligamentous attachments in the forehead were above 10 N. These results indicate that osteoperiosteal ligamentous attachments develop in the rather medial region of the eyebrow and have a tensile strength adequate enough to maintain the medial eyebrow. Thus, the current study provides surgeons with detailed anatomic information that can be used as a valuable reference for forehead rejuvenation procedures.

Characterisation of skin barrier function using bioengineering and biophysical techniques.

PURPOSE: To characterise skin barrier function in vivo at two distinct anatomic sites using minimally invasive bioengineering and biophysical tools. METHODS: In healthy human volunteers, the quantities of stratum corneum (SC) per unit area of skin on the forearm and forehead were quantified by gravimetric and imaging techniques. Organisation of the SC intercellular lipids was evaluated as a function of position using attenuated total reflectance infrared spectroscopy (ATR-IR). The constituents of natural moisturising factor (NMF) were extracted from tape-stripped samples of the SC and by reverse iontophoresis; 21 components were identified and quantified by liquid chromatography with mass spectrometric detection. RESULTS: SC was quantified more accurately by imaging and was significantly thinner on the forehead than on the forearm. Intercellular lipids were more disordered near the skin surface at both sites; however, throughout forearm SC, the lipids were substantially better organised than those in the forehead. Compositionally, the NMF from forearm and forehead SC was similar, but the total amount extractable from the forehead was smaller. CONCLUSION: Taken together, the bioengineering and biophysical techniques employed demonstrate, in a complementary, objective and quantitative fashion, that SC barrier function on the forehead is less competent than that on the forearm.

Changes in serum free testosterone, sleep patterns, and 5-alpha-reductase type I activity influence changes in sebum excretion in female subjects.

BACKGROUND/PURPOSE: Sebum is thought to play an important role in acne vulgaris and sebum excretion rate (SER) is often used as a marker of efficacy in acne studies. This study explored factors that could induce intra-subject variability in SER. METHODS: SER was measured twice, 7 days apart, on the forehead of 40 healthy subjects. At each visit, the following parameters were also evaluated: serum androgen levels, 5-alpha-reductase type I gene expression, forehead temperature, sleep habits, diet, facial washing routine, and UV exposure. RESULTS: There was a positive correlation between the time subjects fell asleep on Day 0 and the change in SER for the left (P = 0.010; R = 0.402) and right sides (P = 0.002; R = 0.467) of the forehead. There was a significant inverse correlation between SER and 5-alpha-reductase type 1 expression and between free testosterone levels and 5-alpha-reductase type 1 expression. In sub-analyses performed on men and women, these correlations were only significant for women. CONCLUSION: Variations in sleep patterns, free testosterone, and 5-alpha-reductase type 1 activity are associated with changes in sebum excretion in women. This could explain some of the inter-subject variability in SER measured between visits in clinical studies.

ß-Adrenergic blockade enhances coronary vasoconstrictor response to forehead cooling.

Forehead cooling activates the sympathetic nervous system and can trigger angina pectoris in susceptible individuals. However, the effect of forehead cooling on coronary blood flow velocity (CBV) is not well understood. In this human experiment, we tested the hypotheses that forehead cooling reduces CBV (i.e., coronary vasoconstriction) and that this vasoconstrictor effect would be enhanced under systemic ß-adrenergic blockade. A total of 30 healthy subjects (age range, 23-79 years) underwent Doppler echocardiography evaluation of CBV in response to 60 s of forehead cooling (1°C ice bag on forehead). A subset of subjects (n = 10) also underwent the procedures after an intravenous infusion of propranolol. Rate pressure product (RPP) was used as an index of myocardial oxygen demand. Consistent with our first hypothesis, forehead cooling reduced CBV from 19.5 ± 0.7 to 17.5 ± 0.8 cm/s (P < 0.001), whereas mean arterial pressure increased by 11 ± 2 mmHg (P < 0.001). Consistent with our second hypothesis, forehead cooling reduced CBV under propranolol despite a significant rise in RPP. The current studies indicate that forehead cooling elicits a sympathetically mediated pressor response and a reduction in CBV, and this effect is augmented under ß-blockade. The results are consistent with sympathetic activation of ß-receptor coronary vasodilation in humans, as has been demonstrated in animals.

Effects of treadmill running and fatigue on impact acceleration in distance running.

The effects of treadmill running on impact acceleration were examined together with the interaction between running surface and runner's fatigue state. Twenty recreational runners (11 men and 9 women) ran overground and on a treadmill (at 4.0 m/s) before and after a fatigue protocol consisting of a 30-minute run at 85% of individual maximal aerobic speed. Impact accelerations were analysed using two lightweight capacitive uniaxial accelerometers. A two-way repeated-measure analysis of variance showed that, in the pre-fatigue condition, the treadmill running decreased head and tibial peak impact accelerations and impact rates (the rate of change of acceleration), but no significant difference was observed between the two surfaces in shock attenuation. There was no significant difference in acceleration parameters between the two surfaces in the post-fatigue condition. There was a significant interaction between surface (treadmill and overground) and fatigue state (pre-fatigue and post-fatigue). In particular, fatigue when running overground decreased impact acceleration severity, but it had no such effect when running on the treadmill. The effects of treadmill running and the interaction need to be taken into account when interpreting the results of studies that use a treadmill in their experimental protocols, and when prescribing physical exercise.

Temporal and spatial dispersion of human body temperature during deep hypothermia.

BACKGROUND: Clinical temperature management remains challenging. Choosing the right sensor location to determine the core body temperature is a particular matter of academic and clinical debate. This study aimed to investigate the relationship of measured temperatures at different sites during surgery in deep hypothermic patients. METHODS: In this prospective single-centre study, we studied 24 patients undergoing cardiothoracic surgery: 12 in normothermia, 3 in mild, and 9 in deep hypothermia. Temperature recordings of a non-invasive heat flux sensor at the forehead were compared with the arterial outlet temperature of a heart-lung machine, with the temperature on a conventional vesical bladder thermistor and, for patients undergoing deep hypothermia, with oesophageal temperature. RESULTS: Using a linear model for sensor comparison, the arterial outlet sensor showed a difference among the other sensor positions between -0.54 and -1.12°C. The 95% confidence interval ranged between 7.06 and 8.82°C for the upper limit and -8.14 and -10.62°C for the lower limit. Because of the hysteretic shape, the curves were divided into phases and fitted into a non-linear model according to time and placement of the sensors. During cooling and warming phases, a quadratic relationship could be observed among arterial, oesophageal, vesical, and cranial temperature recordings, with coefficients of determination ranging between 0.95 and 0.98 (standard errors of the estimate 0.69-1.12°C). CONCLUSION: We suggest that measured surrogate temperatures as indices of the cerebral temperature (e.g. vesical bladder temperature) should be interpreted with respect to the temporal and spatial dispersion during cooling and rewarming phases.

Comparing finger and forehead sensors to measure oxygen saturation in people with chronic obstructive pulmonary disease.

BACKGROUND AND OBJECTIVE: Oxyhaemoglobin saturation of arterial blood is commonly measured using a finger sensor attached to a pulse oximeter (SpO(2)). We sought to compare SpO(2) measured using finger and forehead sensors with oxyhaemoglobin saturation in arterialized capillary samples (ACS) in people with chronic obstructive pulmonary disease (COPD) during exercise. METHODS: During aerobic exercise, SpO(2) was measured continuously by two pulse oximeters: one connected to a finger sensor and to a forehead sensor. Before and after the task, ACS were collected to provide a minimally invasive reference measure of oxyhaemoglobin saturation. Patients with COPD were eligible for inclusion if they desaturated when walking by >4% from resting levels to <90%. Current smokers and those prescribed supplemental oxygen were excluded. RESULTS: Fourteen participants completed the study (forced expiratory volume in 1 s = 35 ± 10% predicted). Compared with ACS, SpO(2) measured via the finger sensor was 2% lower (limit of agreement 3%), and SpO(2) measured via the forehead sensor was 2% higher (limit of agreement 4%). Differences were not systematic. The change in oxygen saturation during exercise was similar among the finger sensor (-7; 95% confidence interval (CI): -4 to -10%), forehead sensor (-7; 95% CI: -3 to -10%) and ACS (-6; 95% CI: -3 to -9%). CONCLUSIONS: Oxygen saturation measured using the forehead sensor was higher than that measured in ACS. Assuming that oxygen saturation in ACS is slightly less than arterial blood, forehead sensors may yield measures more concordant with arterial blood. Both sensors detected exercise-induced desaturation.

Technical note: comparing von Luschan skin color tiles and modern spectrophotometry for measuring human skin pigmentation.

Prior to the introduction of reflectance spectrophotometry into anthropological field research during the 1950s, human skin color was most commonly classified by visual skin color matching using the von Luschan tiles, a set of 36 standardized, opaque glass tiles arranged in a chromatic scale. Our goal was to establish a conversion formula between the tile-based color matching method and modern reflectance spectrophotometry to make historical and contemporary data comparable. Skin pigmentation measurements were taken on the forehead, inner upper arms, and backs of the hands using both the tiles and a spectrophotometer on 246 participants showing a broad range of skin pigmentation. From these data, a second-order polynomial conversion formula was derived by jackknife analysis to estimate melanin index (M-index) based on tile values. This conversion formula provides a means for comparing modern data to von Luschan tile measurements recorded in historical reports. This is particularly important for populations now extinct, extirpated, or admixed for which tile-based measures of skin pigmentation are the only data available.

Investigation of the relationship between wrinkle formation and deformation of the skin using three-dimensional motion analysis.

BACKGROUND: Although there have been many studies investigating facial movements using three-dimensional (3D) quantitative analysis, the possible relationship between the levels of wrinkles and the movement distance of facial skin has previously not been reported. METHOD: Forty-four healthy Japanese women (from 20 to 50 years, average = 47.7 ± 3.6 years) were recruited for this study with written informed consent. Infrared reflective marks were attached on their forehead skin, and then moving images of facial skin motions (raising the eyebrows) were captured using two infrared cameras under infrared ray irradiation. Calibration for the absolute value of distance was established using an exact one-point 3-m cube having infrared reflective marks at each apex. The two pupils and the top of the nose were setup as fixed standard points. 3D motion analysis was then carried out using Move-tr/3D(™) software to determine the absolute distances of skin surface movements. Levels of wrinkles were determined using a 3D roughness analyzer (PRIMOS) directly at rest and when raising the eyebrows. RESULTS: The wrinkle levels at rest showed a relatively high and significant correlation with wrinkles when strongly raising the eyebrows. Although the wrinkle levels at rest showed no correlation with the movement distance, the wrinkle levels when raising the eyebrows showed a significant correlation with the movement distance. The ratio of change based on the distance between the marks at rest and when raising the eyebrows showed similar correlation results. CONCLUSIONS: These results suggest that both the levels of skin deformation caused by movements and the wrinkles at rest are important factors that determine the wrinkle level when raising the eyebrows. However, the level of skin deformation is not important for wrinkle levels at rest, which indicates that other factors such as skin elasticity are also important for the formation of wrinkles.

Improving pulse oximetry accuracy by removing motion artifacts from photoplethysmograms using relative sensor motion: a preliminary study.

To expand applicability of pulse oximetry in low-acuity ambulatory settings, the impact of motion on extracted parameters as saturation (SpO2) and pulse rate (PR) needs to be reduced. We hypothesized that sensor motion relative to the skin can be used as an artifact reference in a correlation canceller to reduce motion artifacts in photoplethysmograms (PPGs), in order to improve SpO2 and PR measurements. This has been proven true in in vivo measurements, where forehead PPGs have been obtained while subjects are walking on a treadmill and relative sensor motion has been measured via self-mixing interferometry. By using relative motion in a normalized least mean square algorithm, the standard deviation of SpO2 and PR errors is on average reduced by 31 % and 13 %, respectively.

Validated assessment scales for the upper face.

BACKGROUND: Age-related upper face changes such as wrinkles, lines, volume loss, and anatomic alterations may affect quality of life and psychological well-being. The development of globally accepted tools to assess these changes objectively is an essential contribution to aesthetic research and routine clinical medicine. OBJECTIVE: To establish the reliability of several upper face scales for clinical research and practice: forehead lines, glabellar lines, crow's feet (at rest and dynamic expression), sex-specific brow positioning, and summary scores of forehead and crow's feet areas and of the entire upper face unit. METHODS AND MATERIALS: Four 5-point photonumerical rating scales were developed to assess glabellar lines and sex-specific brow positioning. Twelve experts rated identical upper face photographs of 50 subjects in two separate rating cycles using all eight scales. Responses of raters were analyzed to assess intra- and interrater reliability. RESULTS: Interrater reliability was substantial for all upper face scales, aesthetic areas, and the upper face score except for the brow positioning scales. Intrarater reliability was high for all scales and resulting scores. CONCLUSION: Except for brow positioning, the upper face rating scales are reliable tools for valid and reproducible assessment of the aging process.

Regional variations in percutaneous absorption.

BACKGROUND: In its simplest definition, percutaneous absorption (PA) is the amount of substance that passes through the stratum corneum compared with the amount applied. The study of the PA of substances is relevant to the fields of dermatopharmacology and occupational medicine. The quantity and rate in which a given chemical absorbs through the skin depend on a multitude of variables. One obvious determinant of PA is the application site. This overview summarizes currently available data on the topic of regional variations in PA and possibly suggests a direction for future research efforts. METHODS: Searches were performed in Medline and EMBASE. Extensive bibliographical research was performed in order to identify additional relevant data sets using Web of Science. Results were screened for inclusion of more than one anatomical site, the use of validated methods, and the use of human subjects. RESULTS: We identified eight relevant studies, from which we present data. CONCLUSION: Determining regional variations in PA is a complex yet critically important task. Current data sets are scarce and inadequate for drawing complete conclusions, but the data seem to suggest increased PA in the forehead and genital skin compared with other anatomical regions. It is our hope that, with the advent of new technologies, an anatomical PA map will begin to emerge from the data. Such descriptive understanding will guide investigation into the mechanisms involved in determining anatomical site differences in PA.

Comparison of an in-helmet temperature monitor system to rectal temperature during exercise.

Body temperature monitoring is crucial in helping to decrease the amount and severity of heat illnesses; however, a practical method of monitoring temperature is lacking. In response to the lack of a practical method of monitoring the temperature of athletes, Hothead Technologies developed a device (HOT), which continuously monitors an athlete's fluctuations in body temperature. HOT measures forehead temperature inside helmets. The purpose of this study was to compare HOT against rectal temperature (Trec). Male volunteers (n = 29, age = 23.5 ± 4.5 years, weight = 83.8 ± 10.4 kg, height = 180.1 ± 5.8 cm, body fat = 12.3 ± 4.5%) exercised on a treadmill at an intensity of 60-75% heart rate reserve (HRR) (wet bulb globe temperature [WBGT] = 28.7° C) until Trec reached 38.7° C. The correlation between Trec and HOT was 0.801 (R = 0.64, standard error of the estimate (SEE) = 0.25, p = 0.00). One reason for this relatively high correlation is the microclimate that HOT is monitoring. HOT is not affected by the external climate greatly because of its location in the helmet. Therefore, factors such as evaporation do not alter HOT temperature to a great degree. HOT was compared with Trec in a controlled setting, and the exercise used in this study was moderate aerobic exercise, very unlike that used in football. In a controlled laboratory setting, the relationship between HOT and Trec showed favorable correlations. However, in applied settings, helmets are repeatedly removed and replaced forcing HOT to equilibrate to forehead temperature every time the helmet is replaced. Therefore, future studies are needed to mimic how HOT will be used in field situations.